BAGHDAD, Iraq (CNN) -- An Iraqi TV reporter who threw his shoes at President Bush during a news conference remained in custody Monday, while judicial officials decided whether to charge him with assault.

TV reporter Muntadhar al-Zaidi, in a file photo, was jailed after throwing his shoes at President Bush.

Muntadhar al-Zaidi, a reporter for the TV channel Al-Baghdadia, faced testing for alcohol and drugs to determine his state of mind, said a government official, who requested anonymity.

At Sunday's news conference, the journalist whipped off his shoes and hurled them at Bush during the president's unannounced stop in Baghdad. The reporter called his shoe-throwing, a traditional insult in Arab culture, a "farewell kiss" to a "dog" who launched the 2003 invasion of Iraq.

"I don't know what the guy said, but I saw his sole," the president joked.

Meanwhile, Al-Baghdadia is devoting round-the-clock coverage to the incident and calling for the immediate release of the reporter whose co-workers describe as usually "calm and polite."

In a statement read on the air, Al-Baghdadia said that al-Zaidi should be freed "in accordance with democracy and freedom of expression Iraqis were promised by the new era and American authorities."

The channel also ran the reporter's image with what it said were messages of support from viewers in a crawl at the bottom of the screen and called on Arabs, Muslims and Iraqis to support "your brother."

The network is fielding viewer phone calls about the action, with many people expressing support for al-Zaidi and others saying his behavior was inappropriate.

"What Muntadhar did represents the biggest test for the United States and the Iraqi government -- if they release him or continue detaining him," said Abdul Hamid al-Saeh, a spokesman for the Iraq-owned, Egypt-based network.

The reporter has worked for the channel since 2005.

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Al-Baghdadia said any actions taken against the reporter would be reminiscent of the "violent acts, random arrests, mass graves and personal and public freedoms taken away" during the rule of ousted dictator Saddam Hussein. It called on other Arab countries and journalists to support al-Zaidi's release.

It's unclear what motivated the journalist, but reports suggest that al-Zaidi knows firsthand the anguish of the Iraq war. Al-Zaidi was kidnapped in November 2007 and released three days later, according to Reporters Without Borders.

Al-Zaidi is from Baghdad's Sadr City, one of the country's biggest slums and the site of some of the conflict's bloodiest battles.

His arrest drew an angry protest Monday in Sadr City by followers of anti-American cleric Muqtada al-Sadr. In the Shiite neighborhood, angry people marched to demand the journalist's release, protest the U.S.-Iraqi security agreement and urge the withdrawal of American troops.

Hurling any object is a form of hostility, but in Arab culture, throwing a shoe or striking someone with one is the ultimate form of contempt.

And at Monday's demonstration, the imagery of the shoe-throwing incident conjured anger and pride.

Calling Bush the devil, a Sadrist cleric addressing the crowd condemned the visit of "the leader of evil and terror" and said the president was humiliated in a visit that was meant to celebrate achievements.

Protesters placed a shoe atop a pole with a note saying, "Go Out USA."

Demonstrators chanted: "Listen Bush, we got you out with a pair of shoes," "If we run out of ammunition, we will hit them with shoes," and "America out now."

They carried banners calling for al-Zaidi's release and hoisted flags and posters of Shiite clerics.

One demonstrator described Bush as a "terrorist ... whose hands are covered in children and women's blood." Another pounded a U.S. flag with his shoe, and the flag was torched by protesters. A third pretended to auction the shoe that hit Bush.

After his visit to Iraq, Bush traveled to Afghanistan, where he said U.S.-led forces would maintain their pursuit of Taliban militants, but warned there would be no quick victory.

"They can hide, but we can stay on the hunt," Bush said. "We will keep the pressure on them, because it's in the peaceful people of Afghanistan's interest just like it's in the interest of this country.

"Are there still difficult days ahead? Absolutely," he said. "But are conditions a lot better than they were than they were in 2001? Unquestionably, undoubtedly they're better."

Afghanistan was the original front in the war on the al Qaeda network launched after the September 11, 2001, attacks. A U.S. invasion swiftly deposed the Taliban, the Islamic militia that had harbored al Qaeda, but the leaders of both movements escaped and remain on the run.

Nearly 40,000 U.S. and NATO troops are still in Afghanistan, with the Pentagon expected to shift another three U.S. brigades into the fight by summer. The war has cost the coalition 1,018 dead to date, including 624 Americans.

Iraq has been far more costly to the United States, with more than 4,200 Americans killed and cost estimates of more than $600 billion.

But violence has declined sharply over the past 18 months as former Sunni Arab insurgents turned against Islamic jihadists loyal to al Qaeda in Iraq, which has been blamed for some of the worst attacks of the 5-year-old war.

About 130,000 U.S. troops remain in Iraq, but a recent agreement between Washington and Baghdad calls for American combat units to be out of Iraqi cities next June and to leave the country entirely by the end of 2011.